We propose to study problems of the natural history and pathogenesis of primary retinitis pigmentosa (RP). Psychophysical measures including absolute rod thresholds, color thresholds, temporal resolution, and chromaticity discrimination, electroretinographic measures of rod and cone thresholds and temporal characteristics, reflection densitometric measures of rhodopsin concentration, and ICG and fluorescein angiographic measures of retinal and choroidal circulation will be made on RP patients and normal controls at closely spaced intervals for a period of at least five years. In addition, we will collaborate with a research group at N.E.I. by supplying them with blood samples from our RP patients to be used in their biochemical and immunological tests of various etiological hypotheses.